Puberty, when it starts.

:-| you will see the underlined symptom Under arm hair, Breast Budding and growth, deeper voice,pimples may happen ect.

Learn about it

If a boy, the sort of changes you will see first are: Growth spurt, testicular enlargement, hair on lower legs, pubic hair, penile enlargement. The other changes happen later.

If a girl, you will also have a growth spurt right at the beginning of puberty. Most girls start with breast enlargement, although in about a third, pubic hair growth comes first.

Girls tend to start first - age 8-13 is typical. Boys tend to be a year or two behind.